November 8, 2017 – Rain or showers today through Friday. Minimal mountain travel impact due to high snow levels. Dry Saturday with rain and mountain snow again early next week with continued high snow levels. Breezy winds today and Thursday and again Sunday and Monday.
Light rain falling across the northwest corner of the state this morning as a Pacific Frontal system approaches the coast. Light prefrontal precipitation is expected to move across the north state today with rain or higher elevation snow remaining mainly north of the Stockton area. Models have slowed the front a bit so backed off on timing of precipitation progression slightly especially during the morning hours today.
Cloud cover and airmass cooling will bring down high temperatures today but snow levels will remain relatively high so mountain travel impacts will be minimal. South winds will be on the increase as the front approaches especially over the higher terrain. Main frontal band pushes through NorCal tonight and into the Sierra by Thursday morning.
Most areas will see some precipitation with amounts similar to the system that went through at the end of last week. Heaviest precipitation will occur over the northern Sierra where orographics have the largest role.
Snow levels will drop slightly behind the front Thursday night but still remain relatively high so mountain snow impacts remain minimal. Breezy winds continue through Thursday but diminish late Thursday into Friday as the frontal band lifts out of the region. A secondary upper level shortwave trough will push through NorCal late Friday and Friday night bringing a continued threat of light precipitation. Snow levels remain high with this system so mountain travel impacts remain minor.
Upper ridging pushes up temporarily over the west coast bringing an end to the precipitation threat on Saturday with some warning and lighter winds.
Extended discussion (Sunday through Wednesday)
Pacific frontal system is projected to bring light precipitation into areas north of I80 by Sunday afternoon, becoming widespread Sunday night with moderate intensity over the mountains. Monday could see some locally heavier convective showers, depending on the timing of a cold front moving through. Accumulating mountain snow is possible at pass levels Monday night, along with gusty winds.
A weak system passing through the Pacific Northwest could bring light precipitation into the southern Cascades, northern Coastal Range, and northern Sacramento Valley Tuesday through Wednesday.